Electrical measuring instrument.



-No. 698,682. Patented Apr. 29, I902. v T. DUNCAN. Y

ELECTRICAL MEASURING INST BUMENT. (Application filed Jan. 2, 1900.Renewed Dec. 16, 1901.

(No Model.)

lmflnf 3%MM Z@ D L E.

THOMAS DUNCAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE SIEMENS & HALSKEELECTRIC COMPANY OF AMERICA, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

ELECTRICAL MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 698,682, dated April29, 1902.

Application filed January 2,1900. Renewed December 16, 1901. Serial No.86,062. (No model.)

To all whom it may concern:-

Be it known that I, THoMAs DUNCAN, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Im provement in Electrical MeasuringInstruments, (Case No. 344,) of which the following is a full, clear,concise, and exact description, reference being bad to the accompanyingdrawings, forming a part of this specification.

Myinvention relates primarily to alternating-current systems ofdistribution, although certain features of the invention may be employedin connection with other systems of distribution; and the invention hasfor its object the provision of an improved compensating voltmeter whichis adapted to accurately determine the pressure at a distant point in asystem of transmission.

When the pressure at any point distant from the'generating-station isaccurately determined, this pressure may be maintained constant byregulation of theimpressed pressure to compensate for load changes andthe O R drop over the distributing lines due thereto, which variesdirectly as the load.

Two ways have hitherto been frequently practiced for measuring thepressure at a predetermined point in the line distant from thegeneratingstation. A common way is to employ an ordinary voltmeter uponthe station-switchboard which is connected at the distant pointforexample, the center of distributionby means of two pressure-wires, theinstrument thenindicating the pressure at the distant point. When thedistance between the distant predetermined point of the line and thegenerating-station is great, the expense of these pressure-wires issignificant when a great number of machines are used. It has also beenthe practice to employ a Voltmeter included in a circuit'with twosecondary coils whose primaries are respectively in series with a. maintransmission-line and as the effect of the series transformer-coil isthe same irrespective of the distribution of the load.

By means of my present invention I am enabled to dispense with apressure-wire employed in one of the aforesaid prior methods to reducethe cost of line construction and at the same time maintain accuracy inthe determination of the pressure at the distant point of distributionwhere the pressure is to be measured. I am also enabled to overcome thedisadvantages of the second aforesaid prior method of determining thepressure at points distant from the generator-station in that I amenabled to accurately determine this pressure irrespective of thedistribution of the load.

In practicing myinvention I preferably employ a meter having twowindings, one for interposition between a point of the transmissionsystem at the generator and a second point distant from the generator. Atorque is created by this winding which is proportional to the C R dropbetween the connected points. I preferably connect the second windingbetween the mains of the transmission system. A portion of the secondwinding in the preferred embodiment of the invention is in the form of acoil which is rotatably mounted, preferably upon a shaft to which apointer is attached, the subdivided portions of this second windingbeing preferably'included-in series. A scale is provided upon which thepointer may indicate measurements. Where the system of transmission isbeing supplied with current of high pressure, I preferably interposetransformers between each winding of the meter and the source of currenttherefor to reduce the pressure impressed upon these windings.

I will explain my invention more particularly by reference to theaccompanying drawings, in which Figure l diagrammatically indicatesapparatus constructed in accordance with the preferred embodiment of myinvention and a system of distribution with which the said apparatus isassociated. Fig. 2 is a diagrammatic View showing a modification of aninstrument constructed in accordance with my invention.

Like parts are indicated by similar letters of reference in both views.

In Fig. 1 I have illustrated an alternatingcurrent system ofdistribution, a source of alternating current a being shown as supplyingcurrent to translating devices I).

The instrument 0 may be constructed as shown in Fig. l. I have providedtwo stationary field-coils d 6, between which a shaft is placed, a thirdcoil f being mounted to 1'0- tate with the shaft. In order to adapt theinstrument to the measurement of voltages in alternating-current systemsof electrical distribution, the coils thereof are unprovided with ironcores. A pointer g moves with the revoluble coil, a scale 72 beingprovided upon which the pointer may indicate measurements. The coils dand f form parts of the same winding, these coils being shown in series,although I do not wish to be limited to this series arrangement of thecoils.

The instrument illustrated in Fig. 2 is similar to that shown in Fig. l,the portion f being subdivided into two coils. A resistance 7;,extraneous to the winding composed of the parts d and f, is provided toprevent waste of current, a resistance for like purpose being alsoincludedin series with the winding 6. Torsional springs may be providedin the wellknown way to act against the torques of the instrument.

In the present instance I have illustrated a system ofalternating-current distribution of high electromotive force, andinstead of connecting the windings of the meter directly between themains of the system and the conductor interposed between a point of thetransmissioncircuit n near the generator and a distant point 0 I employtransformers l and m, whose primaries are connected, respectively,between the mains of the system and with the said conductor. Thisconductor, it will be observed, is in the present instance in shunt ofone of the mains. The instrument as thus arranged is adapted to effect amovementof the pointer proportional to the algebraic sum of theimpressed pressure and the c r drop. Assuming that there is no load uponthe system the instrument will indicate only the impressed pressure whena load is put upon the system, and as it increases the current in thewinding 6 will increase proportionally to the drop over the lines. Ashas been said, in effect, the winding 6 opposes the magnetizing effectof the winding d, resulting in the indication upon the scale being thedifference between the pressure at the station and the drop over thelines or the actual Voltage at the point of service 0t. a, theinstrument reads the electromotive force at any predetermined point. If,for example, the dynamo-pressure is one hundred and four volts and thedrop over the lines is ,four volts, then the resultant volts indicatedon the instrument will be one hundred and four volts, minus four volts,equaling one hundred volts. I preferably so adjust the windings of theinstrument that the winding receiving current fro m the conductorjoiningthe points of the transmission-circuit n and 0 will produceproportionally twice the torque for a given pressure impressed at itsterminals than that caused by the winding subjected to thegenerator-pressure.

In applications Serial Nos. 87, 88, and 89, filed of even date herewithI have shown systems of direct-current distribution and im proved meansfor measuring the voltage at points in the transmission systems distantfrom the generator. While I have shown transformers for supplyingcurrent to the windings of the instrument, I do not wish to be limitedto this particular means.

While I have herein shown and particularly described one embodiment ofmy invention, it is obvious that changes may readily be effected withoutdeparting from the spirit thereof, and I do not, therefore, wish to belimited to the precise construction shown; but,

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. In asystem of electrical distribution, thecombination with an alternating-currentgenerator supplying current to atransmission-circuit, of a measuring apparatus having avoltmeter-winding subjected to pressure between the generator-terminals,and a second pressure-winding subjected to pressure between a point ofthe transmission-circuit and a second and distant point of thetransmission-circuit where the pressure is to be determined, todetermine the c 1 drop whereby the pressure at distant points of thetransmission-circuit may be readily determined, substantially asdescribed.

2. In asystem of electrical distribution, the combination with analternating-current generator supplying current to atransmission-circuit, of a measuring apparatus having a voltmeter-winding subjected to pressure between the generator-terminals, and a secondpressure-winding subjected to pressure between a point of thetransmission-circuit near the generator and a second and distant pointof the transmission-circuit where the pressure is to be determined,whereby the pressure at a distant point of the transmission-circuit maybe determined, substantially as described.

3. In a system of electrical distribution, the combination with analternating-current generator supplying current to atransmission-circuit, of a measuring apparatus havinga voltmeter-windingsubjected to pressure between the generator-terminals and a secondpressure-winding subjected to pressure between a point of thetransmission-circuit and a second and distant point of the transmissioncir- IIC cuit where the pressure is to be determined, to determine the cdrop, whereby the pressure at distant points of the transmission-circuitmay be readily determined, said second meter-winding subjected topressure between the generator-terminals, and a second pressure-windingsubjected to pressure between a point of the transmission-circuit nearthe generator and a second and distant point of the transmission-circuitwhere the pressure is to be determined, whereby the pressure at adistant point of the transmission-circuit may be determined, said secondwinding receiving current from a conductor in shunt of one side, or aportion of one side of the transmission-circuit, substantially asdescribed.

5. In asystem of electrical distribution, the combination with analternating-current generator supplying current to atransmissioncircuit, of ameasuring instrument havingavoltmeter-windingsubjected to pressure between the generator-terminals, and a secondpressure-winding subjected to pressure between a point of thetransmission-circuit and a distant point of the transmission-circuitwhere the pressure is to be determined, and means whereby said windingsmay cooperate to produce a single actuation of the movable element ofthe meter to measure the pressure at said distant point, substantiallyas described.

6. In asystem of electrical distribution, the combination with analternating-current generator supplying current to a transmission-circuit, of a measuring instrument havinga voltmeter-windingsubjected to pressure between the generator-terminals, and a secondpressure-winding subjected to pressure between a point of thetransmission-circuit and a second, distant point where the pressure isto to be determined, said windings cooperating.

to actuate the movable element of the meter, said windings being adaptedeach to create a torque opposing a torque due to the other whereby aresultant torque is produced to ac' tuate said element to measure thepressure at said distant point, substantially as described.

8. In a system of electrical distribution, the combination with analternating-current generator supplying current to atransmission-circuit, of a measuring instrument having avoltmeter-winding subjected to pressure between the generator-terminals,and asecond pressure-winding subjected to pressure between a point ofthe transmission-circuit and a distant point of the transmission-circuitwhere the pressure is to be determined, and means whereby said windingsmay cooperate to produce a single actuation of the movable element ofthe meter, said windings being adapted each to create a torque opposingthe torque due to theother, whereby a resultant torque is produced toactuate said element to measure the pressure at said distant point,substantially as described.

9. Ina system of electrical distribution, the combination with analternating-current generator supplying current to atransmissioncircuit, of a transformer whose primary is connected betweenthe generator-terminals, a second transformer whose primary is connectedbetween a point of the transmissioncircuit'and a second and distantpoint of the transmission-circuit where the pressure is to bedetermined, and a measuring apparatus having two voltmeter-windingsconnected respectively with the secondaries of the said transformers,substantially as described.

10. In a system of electrical distribution, the combination withan'alternating-current generator supplying current to atransmission-circuit, of a transformer whose primary is connectedbetween the generator-terminals, a second transformer whose primary isconnected between a point of the transmission-circuit and a second anddistant point of the transmission-circuit where the pressure is to bedetermined, and a measuring apparatus having two voltmeter-windingsconnected respectively with the secondaries of the said transformers,the conductor including the primary of the second transformer beingconnected in shunt of a transmission-conductor, or a portion thereof,substantially as described. I w

11. In a system of electrical distribution, the combination with analternating-current generator supplying current to atransmission-circuit, of a transformer whose primary is connectedbetween the generator-terminals, a second transformer whose primary isconnected between a point of the transmission circuit and a seconddistant point where the pressure is to be determined, and a measuringinstrument having two windings connected respectively with thesecondaries of the said transformers,the said windings cooperating toactuate the movable element of the meter to determine the pressure ofthemeter at said distant point, substantially as described.

12. In a system of electrical distribution, the combination with agenerator, of two stationary coils, one subjected to pressure betweenthe generator-terminals, and the other subjected to pressure between apoint near the generator and a distant point of thetransmission-circuit, and a single movable element subjected to theaction of said coils, substantially as described.

13. In a system of electrical distribution, the combination with agenerator, of a measuring instrument having two windings, one subjectedto pressure between the generatorterminals and the other subjected topressure between a point of the transmission-circuit near the generatorand a second and distant point of the transmission-circuit where thepressure is to be determined, the winding that is subjected to pressurebetween the generator-terminals being divided into two coils, one ofwhich is stationary and the other rotatably mounted, the revoluble coilbeing subjected to the action of the remaining coil and winding,substantially as described.

14. In a system of electrical distribution, the combination with agenerator, of a measuring instrument having two windings, one subjectedto pressure between the generatorterminals, and the other subjected topressure between a point of the transmission-circuit near the generatorand a second distant point of the transmission-circuit where thepressure is to be determined, the winding that is subjected to pressurebetween the generatorterminals being divided into two coils which areincluded in series with each other, one of which is stationary and theother rotatably mounted, the latter being subjected to the action of theremaining coil and winding, substantially as described.

15. In a system of electrical distribution, the combination with agenerator, of a measuring instrument having .two windings, one subjectedto pressure between the generatorterminals and the other subjected topressure between a point of the transmission-circuit near the generatorand a second distant point of the transmission-circuit where thepressure is to be determined, the winding that is subjected to pressurebetween the generatorterminals being divided into two OOIlSyOllG ofwhich is stationary and the other rotatably mounted, the revoluble coilbeing subjected to the action of the remaining coil and winding, apointer carried by the revoluble coil,

and a scale upon which the pointer may indicate measurements,substantially as described.

16. In a systemof electrical distribution, the combination with agenerator, of a measuring instrument having two windings, one subjectedto pressure between the generatorterminals, and the other subjected topressure between a point of the transmission-circuit near the generatorand a second distant point of the transmission-circuit where thepressure is to be determined, the winding that is subjected to pressurebetween the generatorterminals being divided into two coils which areincluded in series with each other, one of which is stationary and theother rotatably mounted, the latter being subjected to the action ofthe'remaining coil and winding, a pointer carried by the revoluble coil,and a scale upon which the pointer may indicate measurements,substantially as described.

17. In a system of electrical distribution, the combination with agenerator, of a measuring instrument having two windings, one subjectedto pressure between the generatorterminals and the other subjected topressure between a point of the transmission-circuit near the generatorand a second distant point of the transmissiomcircuit where the pressure is to be determined, the Winding that is subjected to pressurebetween the generatorterminals being divided into two coils, one ofwhich is stationary and the other rotatably mounted, substantially asdescribed.

18. In a system of electrical distribution, the combination with agenerator, of a measuring instrument having two windings, one subjectedto pressure between the generatorterminals, and the other subjected topressure between a point of the transmission-circuit near the generatorand a second, distantpoint of the transmission-circuit where the pressure is to be determined, the winding that is subjected to pressurebetween the generatorterminals being divided into two coils which areincluded in series with each'other, one of which is stationary and theother rotatably mounted, substantially as described.

In witness whereof I hereunto subscribe my name this 20th day ofDecember, A. D. 1899.

THOMAS DUNCAN.

\Vitnesses:

WILLIAM F. MEYER, JAMES W. DALTON.

